Baroreflex Activation Therapy Lowers Blood Pressure in Patients With Resistant Hypertension - Rheos Pivotal Trial

Jul 29, 2011
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Author/Summarized by Author:
Anthony A. Bavry, MD, MPH, FACC
Summary Reviewer:
Christopher P. Cannon, MD, FACC
Trial Sponsor:
CVRx, Inc.
Date Presented:
01/01/2011
Date Published:
01/01/2011
Date Updated:
07/29/2011
Original Posted Date:
07/29/2011
References

Description:

The goal of the trial was to evaluate carotid baroreceptor stimulation compared with no carotid baroreceptor stimulation among patients with resistant hypertension.

Hypothesis:

Carotid baroreceptor stimulation will be safe and effective for the treatment of resistant hypertension.

Study Design

  • Randomized
  • Blinded
  • Parallel

Patient Populations:

  • Patients with systolic blood pressure ≥160 mm Hg, diastolic blood pressure ≥80 mm Hg, or 24-hour average ambulatory blood pressure ≥135 mm Hg treated for at least 1 month with three antihypertensive medications at maximum doses

    Number of enrollees: 265
    Duration of follow-up: mean, 21 months
    Mean patient age: 54 years
    Percentage female: 36%

Primary Endpoints:

  • Co-primary endpoints (all components had to be met to demonstrate overall efficacy and safety):
    • Short-term acute response
    • Long-term sustained response
    • Procedural safety
    • Baroreflex stimulation therapy safety
    • Device adverse events

    Drug/Procedures Used:

    Patients with resistant hypertension and who agreed to have a pulse generator (Rheos System, CVRx, Inc., Minneapolis, MN) implanted to each carotid sinus for carotid baroreceptor stimulation were randomized to group A: the device turned on from months 0-12 (n = 181) versus group B: device turned off for 6 months, then turned on from months 6-12 (n = 84).

    Concomitant Medications:

    At baseline, the following medications were used: diuretics in 96%, beta-blockers in 86%, calcium channel blockers in 65%, angiotensin-converting enzyme inhibitors in 57%, angiotensin-receptor blockers in 47%, alpha-blockers in 12%, and sympatholytic agents in 44%.

    Principal Findings:

    Overall, 265 patients were randomized. Among group A participants at baseline, the mean age was 54 years, 36% were women, 31% were diabetics, 14% had a prior stroke, the mean number of antihypertensive medications was 5.2, and the mean blood pressure was 169/101 mm Hg. The mean follow-up was 21 months.

    At 6 months, ≥10 mm Hg decrease in systolic blood pressure occurred in 54% of group A versus 46% of group B (p = 0.97). The mean decrease in systolic blood pressure was 16 ± 29 mm Hg in group A versus 9 ± 29 mm Hg in group B (p = 0.08).

    At 6 months, freedom from baroreflex stimulation adverse events was 92% in group A versus 89% in group B (p for noninferiority < 0.001).

    At 12 months, freedom from device-related adverse events was 87% in groups A and B combined.

    Among all patients at 30 days, 4.8% had permanent nerve injury, 4.4% had transient nerve injury, 4.8% had general surgical complications, and 2.6% had respiratory complaints.

    Secondary outcome at 6 months: ≤140 mm Hg systolic blood pressure occurred in 42% of group A versus 24% of group B (p = 0.005), and at 12 months, this outcome occurred in 53% of group A versus 51% of group B (p = 0.70).

    Interpretation:

    Among patients with treatment-resistant hypertension, the use of carotid baroreceptor stimulation represents a novel treatment approach. This therapy did not improve the proportion of patients who had a ≥10 mm Hg decrease in systolic blood pressure at 6 months, one of the five co-primary endpoints.

    However, in a secondary outcome, the proportion of patients who achieved ≤140 mm Hg systolic blood pressure at 6 months was greater with carotid stimulation. This procedure required general anesthesia and was associated with an increased risk of permanent nerve injury. By contrast, renal sympathetic denervation (Symplicity HTN-2) lowered systolic blood pressure by at least 10 mm Hg in 84% of patients versus 35% of control patients.

    References:

    Bisognano JD, Bakris G, Nadim MK, et al. Baroreflex Activation Therapy Lowers Blood Pressure in Patients With Resistant Hypertension: Results From the Double-Blind, Randomized, Placebo-Controlled Rheos Pivotal Trial. J Am Coll Cardiol 2011;Jul 28:[Epub ahead of print].

    Presented by Dr. John Bisognano at the ACC.11/i2 Summit, New Orleans, LA, April 5, 2011.

    Keywords: Stroke, Pressoreceptors, Follow-Up Studies, Carotid Sinus, Sympathectomy, Baroreflex, Blood Pressure, Kidney, Hypertension, Diabetes Mellitus


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